Category: Observations

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Coffee review General Home experiments Observations

A pebble puzzle at The Lanes Coffee House, Brighton

The Lanes Coffee House Brighton, Coffee Brighton
The Lanes Coffee House, Brighton

Hidden somewhere deep in “The Lanes” in Brighton is a great little café that goes by the (somewhat appropriate) name “The Lanes Coffee House“. The Lanes is a set of old, narrow streets that form quite a maze, a great place to explore if you are a visitor to Brighton. There are two entrances to The Lanes Coffee House, which is fortunate as we may not have found the ‘front’ entrance while wandering aimlessly around a few weeks ago. With plenty of seats inside, and a few at the back, The Lanes Coffee House has a lot to notice if you like to sit in a café, enjoying your coffee, without the distractions of your phone or laptop. Pictures by a local artist decorate the walls, with each picture featuring a Brighton scene and The Lanes Coffee House in a “Where’s Wally” type format. A window opens up to the narrow lane outside and there is also plenty to notice inside the café where we enjoyed an Americano and Soya hot chocolate. Sadly on the day that we tried The Lanes there weren’t any nut-free cakes at the counter and so, as compensation, we had to have a bag of fudge.

We sat at a table on which there was a tiny metal bucket that was used for holding sugar (see picture). With Brighton being a sea-side town, this immediately conjured up images of sandcastles and picnic sandwiches. The only problem with this image of course is the fact that Brighton has a pebble beach rather than a sandy one. So rather than think about sandcastles I got thinking about something slightly different: If you were to partially fill a bucket with some sand, put a stone from the beach in the bucket and then fill the rest of the bucket with sand, how could you easily retrieve that stone without fishing around in the sand for it?

missing a spade but it is a bucket
Bucket with sugar at The Lanes

This question came up, in a slightly different way, in a paper published nearly 30 years ago called “Why the Brazil nuts are on top“. That paper dealt with the question of why, in a package of mixed nuts, the Brazil nuts (i.e. the largest nuts) were frequently found to be on top when the package was opened. Termed, the “Brazil nut effect”, it turns out that this question is not just an odd bit of physics but has relevance to the packaging industry and earthquake dynamics. If you were to shake the bucket of sand containing that one pebble, the stone would rise up through the sand, eventually coming to the surface. The question is, what is driving this ‘anti-gravity’ type behaviour? Why do the heavy objects rise to the top?

Obviously, being a coffee website, to do the experiment with sand and a stone is a bit, well, dull. So, using dried, used, grounds (well, what do you do with your used coffee grounds?) and a green coffee bean*, I repeated the experiment on a smaller scale, in a shot glass. I put the green bean at the bottom of the shot glass and then covered it with coffee grounds (up to half way up the shot glass). To prevent too much mess, I covered the shot-glass with a piece of clingfilm. In order to avoid too much vertical shaking, the glass was hit repeatedly from the side in order to ‘shake’ it. It took 40 seconds of vigorous shaking but the green bean eventually started to poke above the surface. The heavy large bean had moved up through the glass upon being shaken, just as the Brazil nuts end up on top in a bag of mixed nuts. Just how had that happened?

Brazil nut effect
Now you see it, after shaking the green bean rises to the surface

It turns out that there are several things going on. Firstly, as the 1987 paper discussed, the small grains of sand (or ground coffee) can fall into voids under the large Brazil nut/stone/coffee bean. This has the effect of pushing the nut/stone/coffee bean upwards until it reaches the surface. The coffee bean could move down through the grounds but this would require the collective movement of a large number of coffee grounds under the bean to form a void large enough for the bean to fall into, something that is fairly unlikely. So the coffee bean will move up, the coffee grounds will move down. Then there is an effect that is more familiar to coffee drinkers, convection. The idea here is that although all the particles in the glass (or bucket) can move upwards as the container is shaken, only the small particles can move down again through the small voids created at the sides of the container. Rather like the movement of milk in a hot coffee, this again has the effect that the small particles push the larger particle up.

After this though things start to get more complicated. Along with what has been termed “the inverse Brazil nut effect”, it seems that air pressure may play a role in the Brazil nut effect. Who knew that Brazil nuts could be so complicated! Perhaps though, to finish our train of thought on The Lanes we could turn this effect into a non-physics, almost allegorical, meditation? If we, as a society, are collectively shaken enough, can small, individual actions do what at first seems impossible? I wouldn’t want to push the analogy too far, but it does seem an interesting problem on which to dwell for a further five minutes while you are sipping on your long black (or, as this is officially the first day of summer, your cold brew).

(If you’d rather think about the physics of sandcastles, you can find out more about them here).

*The green coffee bean came from a jute coffee sack that had been given to me by Amoret coffee for my composting worms. Thanks Amoret!

The Lanes Coffee House is at 59D Ship Street Brighton, BN1 1AE

 

Categories
Coffee review Observations Science history slow Tea

Pottering about in Wa cafe, Ealing

Wa cafe, Ealing, pottery, ceramic, bamboo spoon, glass tea pot
Coffee and tea at Wa Cafe, Ealing

There is something somehow inviting in the minimalism that greets you as you walk into Wa Café in Ealing. Behind the glass counter on your left are a series of colourful cakes along with pastries and buns containing more Japanese-style treats such as the Sakura Anpan (a roll filled with red bean paste). The drinks menu features the usual set of coffees with a more extensive tea menu serving different sorts of Japanese tea. We had a long black (which according to London’s Best coffee is from Nude), the Sakura Anpan and a pot of Hoji Cha (roasted green tea). The coffee came in a delightful ceramic cup with a layering in the interior of the cup reminiscent of rock strata of the Earth. The tea arrived in a pot together with a glass that seemed linked to the type of tea that had been ordered. Glancing around the cafe, it was apparent that different teas were served in differently shaped glasses. Was this due to the fact that glass shape can affect the perceived taste of wine and so maybe also tea?

The saucer for the coffee cup featured a carved pattern that, although different, reminded me of the medieval labyrinths that you can find (such as in Chartres Cathedral). But it was the individual style of the pottery that caused me to recollect a story I had discovered while researching a previous Daily Grind article (and then didn’t use at the time).  The story concerned a ship wreck just off the coast of Malaysia which was leading to a reassessment of our ideas about ancient trading routes and population migrations. As pottery is often one of the bits of the cargo that does not degrade significantly under the water, it is pottery that provides clues for some of our ideas about the past.

Wa_coffeecup
Drinking the coffee revealed ‘layers’ in the cup.

For this article on Wa Cafe though, a little digging revealed a recent archaeological discovery that involved not the pottery itself, but what had been in the pots. It had been known for some time that the first pottery found in Japan dated to about 16,000 years ago, and that around 11,500 years ago there was a significant increase in the volume of pottery produced. As this surge in pottery making was coincident with the end of the last ice age, it was thought that this increase in pottery production was driven by the availability of new sources of food as the climate warmed. So, it came as a surprise when the ‘charred surface deposits’ – meaning the bits of food left after cooking, found in the interior of the pots were actually analysed.

Using a general technique called mass spectrometry, the authors of the study investigated what elements could be found in the food deposits on the pots. They particularly looked at the ratio of carbon and nitrogen in the pots. The proportion and type of element in the food remains have been shown to indicate what had been cooked in the pot, whether it was meat, fish or vegetable matter. As the authors analysed the results they found that the pots were used for cooking fish, fish and more fish. From 16,000 years ago and on for a further 9000 years, the pots were used for fish. Although there was a shift towards the consumption of freshwater fish through the time period studied, there was not the significant change to meat and vegetable matter that had been expected prior to this analysis. The function of the pots had remained constant over millennia.

Labyrinths
A medieval labyrinth and the coffee saucer at Wa. It is thought that many labyrinths were used as meditative aids as you walked your way through them. What would you meditate on while drinking your coffee?

This suggests that rather than the increase in pottery production being about a change in function of the pot, the pots had a distinct cultural use that was unchanged through the warming climate. The results of the analysis challenge the preconceived ideas that had been previously been held. The full paper can be found here.

To an untrained and naive eye of course, I wonder if the people using these pots just had some odd recipes for fish. Maybe they made plenty of vegetable soup (which they rarely burned) but always chargrilled the fish in the pot leading to a prevalence of fish in the ‘charred surface remains’. Nonetheless, this is probably just a poor understanding of what the authors meant by ‘charred surface remains’, surely not every cook burns their fish!

Wa Cafe can be found at 32 Haven Green, W5 2NX

 

 

 

Categories
Coffee review Coffee Roasters Observations

Now you see it now you don’t at Bond St Coffee, Brighton

Outside Bond St Coffee Brighton
Bond St on Bond St, Brighton

A couple of weeks back, I tried the lovely Bond St. Coffee in Brighton on the recommendation of @paullovestea from Twitter. It was a Saturday with good weather and it turns out that this particular café is (understandably) very popular and so, sadly, to begin with we could only sit outside. That said, it was a lovely spring day (sunny but a bit chilly) and so it was quite pleasant to watch the world go by (or at least Bond St) while savouring a well made pour-over coffee. All around the café, the street decoration hinted at times past. Across the road what was obviously a pub in times gone by has turned into an oddities store. Air vents to a space underneath the window seating area in Bond Street café itself suggested an old storage space. A seat in the window appeared to have been re-cycled from an old bus seat.

But it was the pour-overs at Bond St. Coffee that had been particularly recommended and they certainly lived up to expectations. I had a Kenyan coffee roasted by the Horsham Roasters. The V60 arrived at our bench seat/table in a metal jug together with a drinking glass. The angle of the Sun caught the oils on the surface of the coffee, reminding me of Agnes Pockels and her pioneering experiments on surface tension. Pouring the coffee into the glass I thought about the different thermal conductivities of glass as compared to metal and how I had put both down on the wooden bench. How was heat being transferred through these three materials? And then, as I placed the metal jug back on the bench I noticed the reflections from the side of the jug and thought, just why is it that you can see through the colourless glass but the metal is grey and opaque?

Metal jug and transparent glass
Metal jug, glass cup. V60 presentation at Bond St Coffee

On one level, this question has a simple answer. Light is an electromagnetic wave and a material is opaque if something in the material absorbs or scatters the incoming light. In a metal, the electrons (that carry the electric currents associated with the metal’s high electrical conductivity) can absorb the light and re-emit it leading to highly reflective surfaces. In glass there are no “free” electrons and few absorbing centres ready to absorb the light and so it is transmitted through the glass.

Only this is not a complete answer. For a start we haven’t said what we mean by ‘glass’. The glass in the photo is indeed transparent but some glasses can be more opaque. More fundamentally though, there is a problem with the word ‘opaque’. For us humans, ‘visible’ light is limited to light having wavelengths from about 400nm (blue) to about 780nm (red). ‘Light’ though can have wavelengths well below 400 nm (deep into the UV and through the X-ray) and well above 780 nm (through infra-red and to microwaves and beyond). We can see the spread of wavelengths of light visible to us each time we see a rainbow or sun dog. Other animals see different ranges of ‘visible’ light, for example, bumble-bees can see into the ultra-violet. So, our statement that glass is transparent while metal is opaque is partly a consequence of the fact that we ‘see’ in the part of the spectrum of light for which this is true.

Sun-dog, Sun dog
Sun dogs reveal the spectrum of visible light through refraction of the light through ice crystals.

For example if, like the bumble-bee, we could see in the UV, some glass may appear quite different from the way it does to us now. Even though the glass in the photo lacks the free electrons that are in the metallic jug, there are electrons in the atoms that make up the glass that can absorb the incident light if that light has the right energy. There are also different types of bonds between the atoms in the glass that can also absorb light at particular energies. The energy of light is related to its frequency (effectively its colour*). Consequently, if the energy (frequency/ wavelength) of the light happens to be at the absorption energy of an atom or an electron in the glass, the glass will absorb the light and it will start to appear more opaque to light of that colour. Many silicate glasses absorb light in the UV and infra-red regions of the electromagnetic spectrum while remaining highly transparent in the visible region. High purity silica glass starts to absorb light in the UV at wavelengths less than approx 160nm†. Ordinary window glass starts to absorb light in the nearer UV†. In fact, window glass can start to absorb light below wavelengths of up to ~ 300 nm, the edge of what is visible to a bumble bee: The world must appear very different to the bumble bee. At the other end of the scale, chalcogenide based glasses absorb light in (our) visible range but are transparent in the infra-red.

Looking at how materials absorb light, that is, the ‘absorption spectrum’, enables us to investigate what is in a material. It is in many ways similar to a ‘fingerprint’ for the material. From drugs discovery to archaeology, environmental analysis to quality control, measuring how a material absorbs light (over a wider range of frequencies than we can see) can tell us a great deal about what is in that material.

Perhaps you could conclude that whether something is opaque or crystal clear depends partly on how you look at it.

 

Bond St Cafe is on Bond St, Brighton, BN1 1RD

*I could add a pedantic note here about how the colour that we see is not necessarily directly related to the frequency of the light. However, it would be fair to say that a given frequency of light has a given ‘colour’ so blue light has a certain frequency, red light a different frequency. Whether something that appears red does so because it is reflecting light at the frequency of red light is a different question.

†”Optical properties of Glass”, I Fanderlik, was published by Elsevier in 1983.

Categories
Home experiments Observations slow

Something brewing in my V60

kettle, V60, spout, pourover, v60 preparation
The new V60 “power kettle”

It was my birthday a short while ago and someone who knows me well got me a perfect present: a kettle specially adapted for making pour-over V60 style coffees. Until this point I had been struggling with a normal kettle with it’s large spout but now, I can dream that I pour like a barista. Of course, it is important to try out your birthday present as soon as you receive it. And then try it again, and again, just to make sure that it does really make a difference to your coffee. So it is fair to say, that recently I have been enjoying some very good coffees prepared with a variety of lovely beans from Roasting House and my new V60/V60 kettle combination.

Spending the time to prepare a good coffee seems to make it even more enjoyable (though it turns out that whether you agree with this partly depends on why you are drinking coffee). Grinding the beans, rinsing the filter, warming the pot, the whole process taken slowly adds to the experience. But then, while watching the coffee drip through the filter one day, I saw a coffee drop dance over the surface of the coffee. Then another one, and another, a whole load of dancing droplets (video below). Perhaps some readers of Bean Thinking may remember a few months back a similar story of bouncing droplets on soapy water. In that case, fairly large drops of water (up to about 1cm wide) were made to ‘float’ on the surface of a dish of water that had been placed on a loudspeaker.

Sadly, for that initial experiment the coffee had been made undrinkable by adding soap to it. The soap had the effect of increasing the surface viscosity of the droplets which meant that the drop could bounce back from the vibrating water surface before it recombined with the liquid. Adding soap to the coffee meant that these liquid drops could ‘float’ (they actually bounce) on the water for many minutes or even longer (for more of the physics behind this click here).

science in a V60
A still from the video above showing three drops of coffee on the surface.

On the face of it, there are some similarities between the drops dancing on the coffee in my V60 and these bouncing droplets. As each drop falls from the filter, it creates a vibration on the surface of the coffee. The vibration wave is then reflected back at the edges of the V60 and when the next drop falls from the filter it is ‘bounced’ back up by the vibration of the coffee.

But there are also significant differences. Firstly, as mentioned, there was no soap added to this coffee (I was brewing it to drink it!). This means that the viscosity of the drops should be similar to that of ordinary water. Although water drops can be made to bounce, the reduced viscosity means that this is less likely. Secondly, the water is hot. This acts to reduce the viscosity still further (think of honey on hot toast). Perhaps other effects (such as an evaporation flux or similar) could be having an effect, but it is noticeable that although the drops “live” long enough to be caught on camera, they are not very stable. Could it be that the vibrations caused by the droplets hitting the coffee are indeed enough to bounce the incoming droplets back up but that, unlike the soapy-water, these “anti-bubbles” do not survive for very long? Or is something deeper at play? I admit that I do not know. So, over to you out there. If you are taking time to make coffee in a V60, why not keep an eye out for these bouncing droplets and then do some experiments with them. Do you think that the bounce vibration is enough to sustain the bouncing droplet – does the speed of pour make a difference? Is it associated with the heat of the coffee? I’d be interested to hear what you think.

(The original soapy-coffee bouncing droplet video).

If you see anything interesting or odd in your coffee, why not let me know, either here in the comments section below, e-mail, or over on Twitter or on Facebook.

Categories
Coffee review General Observations Science history slow

Ripples from the past at Fleet St Press

flash camera, aeropress, sand timers, coffee at Fleet St Press
Window display at Fleet St Press

As the name suggests, there is a lot of history behind the café at 3 Fleet St (the Fleet Street Press). Not only is it just around the corner from the Devereux (which was once the “Grecian” where Halley met Newton), it is a few doors down from the site of the second ever coffee house established in London (the “Rainbow” was at number 15). There is also plenty of history in the café itself. Fleet St Press operates from a listed building, considered especially noteworthy for its 1912 shop interior (ie. the café). The stained glass at the back of the shop (which was nearly the subject of this cafe-physics review) is apparently original while a sign (for “Tobacco blenders”) in the front window hints at the building’s previous use.

Inside, a row of tall stools offers seating along the wall while a large table at the front of the café offers a space to sit more comfortably to enjoy your coffee. We enjoyed a very nice long black (coffee from Caravan) and a soya hot (white) chocolate. The staff were friendly and it was a lovely space to spend a while. Keep-cups and other coffee making equipment are on sale just next to the counter and the café is just full of things to notice. It’s not just the stained glass. The window to the left of the main door has been stocked with a film camera with flash (presumably a nod to the Fleet St of old), an aeropress, a series of sand-timers and many other items of distraction. We sat at the window which had a good view towards the Royal Courts of Justice and two wonky K2 telephone boxes. Just across the passageway from the phone boxes was a post box and this got me thinking about communication and how we communicate with each other.

soy hot white chocolate
An interesting concept. A white chocolate hot chocolate made with soya milk

In an editorial to a book that rolled off one of Europe’s first printing presses, the Bishop of Aleria, Giovanni de Bussi wrote that printing could be considered an act of generosity “the act of sharing what was hoarded”*†. Since then, the newspapers of the old Fleet St have made way for coffee shops and the papers for the internet. The ‘snail mail’ post box across the road has been almost superseded by email or other forms of internet communication. The telephone box, replaced by mobile phones or Skype. Although we may feel overloaded with information, our ancestors felt the same way. Even in the 1640s it was claimed that they were living in times of a media explosion in which there were just too many books*.

So, rather than look at how the scribe gave way to the printing press, books to newspapers, letters to telegraphs and then telephones and now email, Twitter and instant messaging, perhaps it is worth dwelling a short while on what underlies all of these. Indeed, we are so used to what underlies these communication techniques that we may not even notice it.

Writing.

It may be an obvious point but none of these communication methods would have been possible were it not for writing. Given that Homo sapiens are thought to have come out of Africa some 200 000 years ago, and have been farming since 13000 – 8000 BCE, it is perhaps surprising that the first record that we have of a writing system was not until ~3500 BCE. Writing is thought to have originated in Sumer, Mesopotamia as pictographs. Phonographic writing was not developed until later. Shortly afterwards it was again ‘invented’ in Egypt (3150 BCE) and separately in China (1200 BCE) and MesoAmerica (~500BCE). Writing is a surprisingly recent phenomenon.

K2 phone boxes and a post box
The view from the window at Fleet St Press

As with the fixtures at Fleet St Press, clues from these earlier cultures pervade the space around us rather like the ghost signs of advertising past. The tobacco sign above the door is suggestive of former occupiers Weingott and Sons. Famous for their pipes, they ran a shop on the site from the mid-nineteenth century until the 1930s. Meanwhile, the writing systems of the ancients lives on both in our alphabet and in our time keeping. Even the name ‘alphabet’ resonates with the history of the Greek “alpha, beta” and the Hebrew “Aleph, Beth” (themselves originating from the Phoenician). The Babylonian number system meanwhile, which dates from around 1800 BCE and used base 60 to count (i.e. rather than 1-9, their number system counted 1-59) echoes down the ages. It is thought that remnants of this system remain both in how we count the degrees of a circle (360) and how we tell the time (60 minutes in an hour, 60 seconds in a minute).

Signs and systems that are both instantly familiar and a ghostly ripple from the people of the past.

Fleet St Press can be found at 3 Fleet St, EC4Y 1AU.

*E.L. Eisenstein, “Divine Art, Infernal Machine, the reception of printing in the West from first impressions to the sense of an ending”, University of Pennsylvania Press, (2012)

†Quote from de Bussi is as quoted in Divine Art, Infernal Machine on p 15. 

Some interesting anecdotes about the history of communication can be found in Robert Winston “Bad Ideas, An arresting history of our inventions” Bantam books, (2010),

Also recommended “A history of mathematics, from Mesopotamia to modernity”, L Hodgkin, Oxford University Press, (2005)

 

 

Categories
Coffee review General Observations Sustainability/environmental Tea

Reduce, Re-use, Recycle at Attendant

The outside of Attendant on Foley St
Attendant Coffee, Foley St

I was not initially going to do a cafe-physics review of Attendant. It wasn’t that I didn’t enjoy the coffee, I did. I had a very well prepared V60 which went very well with a lovely chocolate brownie. Nor was it that there was nothing to see at Attendant. No, it was quite the opposite. Part of the point of the Attendant seems to be its location. You see, if you were not aware of it already, Attendant is to be found in a (no-longer-used), underground, gentlemen’s toilet. Although they have been thoroughly cleaned, various fixtures (19th century urinals and cisterns) remain in place. Modern (deliberate) graffiti adorns the walls as you walk in. Understandably, there are no windows to gaze out of in this café. It is, in many ways, a very interesting place to visit and the coffee is certainly worth a visit too. However, it is difficult to do a review which is, after all, about noticing something unusual, when the former use of this space is almost shouting at you. I thought about doing a review based on how the shape of the coffee cup can influence the flavour of  the coffee that you perceive. Yet somehow, writing a review on anything other than the fact that this is a re-use of an interesting space seemed, almost, perverse. So I left it. Until that is, UK Coffee Week came along.

UK Coffee Week raises awareness and money for Project Waterfall which in turn aims to help provide clean water and sanitation for coffee growing communities. Currently, Project Waterfall works in three countries, Tanzania, Rwanda and Ethiopia. In these countries a large number of the rural population lack basic access to drinking water while a greater number do not have access to sanitation facilities. Clearly this can lead to health problems. The World Health Organisation estimates that world wide, the drinking water of 1.8m people is contaminated with faeces, while 0.5 million people per year die from diarrhoeal diseases including cholera.

Interesting glassware at the Attendant
Interesting presentation. Coffee at the Attendant.

Perhaps, while sitting in cafés or having breakfast at home, we have a tendency to take water for granted. Certainly I will admit that I can. I’m sitting here writing this enjoying a great cup of coffee with a few biscuits both of which took water to produce. Beyond the obvious water in the kettle for the coffee and the water used for the dough for the biscuits, there is the ‘hidden’ water. The water used to irrigate the coffee crops and the wheat fields or to process the coffee cherry towards the green bean stage. The water used in generating the electricity used to bake the biscuits, or roast the coffee. The water used to clean the utensils between coffee roasts/biscuit batches so that we don’t get food poisoning. The list could go on. Indeed, the UN estimates that producing 1 cup of coffee requires 140 L of water. This figure though presumably cannot include the private water needs of the individuals who work on the coffee plantations. We all need water and we all need it to be clean.

So, in thinking about our water consumption (and the water consumption of those who help us to enjoy our coffee), we can do a few things during this coffee week 2016. Firstly, we could make a donation towards the work of Project Waterfall (here) or a similar charity that is working to provide clean water and adequate sanitation to those who don’t have it. Secondly, we could take the prompt from Attendant and start to think about where our water comes from. Why from Attendant? Well if you were living on the International Space Station or, to a lesser degree, in Singapore, this question may have an obvious answer. For the rest of us, we are often a little bit removed from direct water recycling, but it’s worth looking more closely at Singapore because they have developed a water strategy that may be of use for more of us in the future.

Reclaimed water NEWater, Singapore
30% of water supplied in Singapore is ‘reclaimed’. Where does your drinking water come from?

Singapore has a population of just over 5.5m (London: 8.6m) with a land area of 719.1 km². As an island, it is surrounded by water and so you may think that water is not a problem for the inhabitants of the city-state. But the water surrounding Singapore is the salt water of the sea and so not easily converted into drinking water. While looking for a solution towards a self-sufficient water supply, Singapore decided to try the recycling route. Through a scheme called NEWater, currently 30% of Singapore’s water supply is from  ‘reclaimed’ water (for reasons that may be obvious, they avoid the word ‘recycled’). The Singaporean authorities aim to make this 55% by 2060. Waste water produced in Singapore undergoes a process of micro-filtration (which takes out suspended particles), reverse osmosis and UV disinfection before being reintroduced to the water supply system. Although most of this reclaimed water is used for industrial processes, the reclaimed water can be added to Singapore’s reservoirs so that it will go into the drinking water supply.

A similar process is used on the International Space Station but there, as it is a closed environment, it is not just the waste water that goes down the drain that is ‘reclaimed’ but the water exhaled by the astronauts and the lab animals on the station. On Earth this would evaporate into the atmosphere, contribute to cloud formation and then rain back down closing the greater water cycle in that way. On the space station, the fact that it is a closed environment means that this moisture too can be ‘reclaimed’. By recycling the water in this way, the inhabitants of the space station avoid having to require too many costly water deliveries from the Earth.

Perhaps, while drinking our coffee (or tea, or even water) today, we can take five minutes to consider where our water comes from as well as considering whether those who contribute to our brew have adequate water supplies themselves. And as it is coffee week, here is that link again to Project Waterfall (Donation button at the bottom of the main Project Waterfall page). Enjoy your coffee.

Note added August 2017: It is with some regret that I have to say that Attendant is not a good place to go if you suffer from allergies. They have started serving almond milk and (according to a Twitter Direct Message received from the Attendant Team) do not adequately clean their steam wand between drinks so as to prevent cross contamination. Their advice to me was that I “should not have any hot drinks or food at our premises as we do not operate a nut free environment at our stores”. There are many good cafes to visit if you suffer from nut allergies, but please avoid this one (or just have a black coffee and enjoy the atmosphere).

 

 

Categories
cafe with good nut knowledge Coffee review Home experiments Observations Tea

Electrifying coffee at the Black Penny

Black Penny coffee London
The Black Penny on Great Queen St

Back in the seventeenth and eighteenth centuries, coffee houses were places to go for debate, discussion or even to learn something new. The Grecian was known for science. Maths instruction (particularly for gambling) could be found with Abraham de Moivre (1667-1754) at Old Slaughter’s on St Martin’s Lane. Other coffee houses were meeting centres for literature, politics, philosophy or even espionage*. Coffee houses became known as “Penny Universities”. The Black Penny on Great Queen St is a café that wants to continue this tradition, with a downstairs “seminar pit” ready to host such discussions. Although the events page still says “coming soon”, if the events do indeed come, this is very much something that’s worth keeping an eye on.

Even without the seminars though, The Black Penny is definitely worth a visit. Entering from the street, the bar is on the left and is stocked with a good looking selection of cakes. We were shown through to the relatively large, bright and airy seating area at the back where a jar of water (infused with cucumber and mint) had been put on the table for us. I had a very good long black and a lovely apple and blackberry muffin with which to take in my surroundings. The muffin was confidently asserted to be nut-free, and so the Black Penny gets a tick in the ‘good nut knowledge’ section on the Daily Grind. The coffee beans were roasted by the Black Penny themselves and while it still says that they serve ‘Alchemy’ coffee on their website, this no longer appears to be the case.

Duracell batteries as coat hooks, battery, batteries
A strange form of coat hook? The things that catch your eye in cafes

Inside, there are some very interesting architectural features to notice, the remains of a ceiling for example (now removed to reveal the roof) and the acoustics introduced by the speaker positioning. Downstairs in the seminar pit there is apparently a very old stove, though I didn’t get to see that on my visit. However, what immediately struck my eye was what appeared to be a series of coat hooks that looked very similar to a well known brand of battery. Quite what these hooks were for or why they looked like batteries I didn’t manage to ascertain, however, it did get me thinking, can you use coffee-power to light an LED?

You may have heard of a potato battery, or a lemon battery. These are often used in science outreach experiments in schools to demonstrate electricity, or the concepts of current/voltage. Made from an ordinary potato (or a lemon), a copper wire is stuck into one end of the potato and a different metal (usually zinc) is stuck into the other end of the potato. At the Black Penny, there were three things left on the table. My coffee, the mint and cucumber infused water and the tea of my accomplice in many of these reviews (I’d eaten the muffin). Which of these would perform better as a battery?

coffee power
Can 6 coffee ‘cells’ with aluminium and copper electrodes light up an LED? (The answer may be in the photo)

Although people suggest using galvanised screws as the source of the zinc electrodes, I didn’t have many of those to hand and so had to manage with aluminium foil for one electrode, copper wire for the other. By putting the aluminium on one side of a shot glass, the copper wire on the other and then filling the glass with coffee, I was able to get 0.5-0.8V across the electrodes when I measured it with my digital multimeter (DMM). Fantastic you may think, almost an AA battery, but then if you were to measure the voltage across the water rather than coffee, you will find that you get a voltage of 0.6-0.7V. The result for tea was, perhaps unsurprisingly, about 0.6V.

But voltage is not the whole story. A battery does not just supply a voltage, it gives a current. The current depends on the electrical conductance of the liquid that the electrodes are in. In the case of the potato or the lemon battery, the acid (phosphoric or citric respectively) means that there are free hydrogen ions in the ‘battery’ between the electrodes which mean the electric current can flow through the circuit. Coffee consists of many acids (chlorogenic, quinic, citric etc etc.) and so it seems sensible to ask if coffee could be used to produce a battery with a current that could power an LED? LEDs require both voltage and current, (1.6V and 10mA for the LEDs used here). Hooking up a series of coffee battery-cells meant that, by 6 ‘cells’, I had 3V across the contacts. However the electric current through the coffee battery was very low (the maximum current I recorded using the low acidity Roasting House Sierra de Agalta Honduran coffee prepared in a cafetière was 155 μA). Although this was higher than the current through water (max 81 μA), it is much lower than the current through white vinegar (770 μA under the same conditions). Consequently, in order to light the LED connected to my coffee battery, I had to add salt to each coffee cell which serves as a way of massively boosting the current through the coffee (salt forms a solution of Na+ and Cl- ions that conduct electricity through the coffee). Though even then, my LED only lit dimly and intermittently.

battery, Volta, Como museum, Como
How it should be done. The “Alessandro Volta Temple” in Como, Italy, is a fantastic place to learn about the history of electricity

Sadly then, I do not see coffee power as a future for lighting in our cafés, (unless you want to use bulletproof coffee with salted butter). However, it has started to make me wonder, could we use a single coffee-cell to monitor the acidity of our coffee? If you find a method of brewing or a particular coffee especially acidic, it should produce a higher current for the same voltage through the cell, or equivalently, the resistance of the coffee-cell should decrease as the acidity of your coffee increases. Although obviously, it would be a bad idea to drink the coffee after putting it into a cell with copper and zinc (or aluminium) electrodes, you could pour a small amount of your coffee into a shot glass to test it while you were drinking the rest of the coffee. I intend on testing this hypothesis over the next couple of weeks but in the meanwhile, if you have thoughts on this to share (or the results of your experiments), please let me know either via the comments section, email, Facebook or Twitter.

The Black Penny is at 34 Great Queen St, WC2B 5AA

* A history of coffee houses can be found in “London Coffee Houses”, Bryant Lillywhite, (1963)

 

Categories
General Observations slow Tea

Happiness is a cup of coffee

stone recycling, slate, slate waterfall, geology
A cafe with a lovely space to enjoy the coffee. Taking time out at Espresso Base

If you are reading this, you clearly have access to a computer. You are also quite possibly connected through social media to friends, colleagues and others through Facebook, Twitter, Instagram or one of the other numerous ways in which we can now connect with each other. And while I would love for you to continue reading, at least for a couple of moments, I would like to ask you how often you take the opportunity to stop?  To stop and turn off your computer or the notifications on your smart phone and just look at what is around you.

This website is really about slowing down and noticing things. Since I believe that science offers a great way of seeing the connectedness of the world around us, I choose to emphasise the science that you can notice around you. It is most likely that you see the world in a different way, sharing some aspects of my point of view, disagreeing with others. However, it seems to me that slowing down and noticing your surroundings, whether you look at the science or another aspect of those surroundings, makes us in some way happier, or at least, generally, more calm. Having a coffee in a café is a great way of doing this. Whether you are interested in the café or the coffee (or indeed both), there is an awful lot to notice and to appreciate in a café. Noticing it of course does depend on keeping the smartphone (tablet or laptop) in your pocket or your bag. Personally, I find it slightly depressing when I see signs in a café saying “free wifi” (though I suspect I am in a minority on that one). And although if we are not used to it, not checking our email while having a coffee can seem to be enforced boredom, I’d hope that we soon realise that such boredom is in fact creative.

Sun-dog, Sun dog
Walking along while texting could mean that you miss seeing a sun dog

Please don’t get me wrong. It is not that I think social media are a bad thing. I have met (either ‘virtually’ or in person) some great and highly interesting people whom I would never have had the opportunity to meet were it not through Twitter/Facebook etc. Each day, I learn something new through the many people whose experience or knowledge I would otherwise never have had the opportunity to ‘tap’. However, just as sometimes it is great to have such interactions, I have found that it is also vital to have times (perhaps even a day a week) when the smartphone is kept firmly in the pocket (or at least, notifications are turned off).

In the UK, we have just got back from a long weekend. Many cafés were closed over the Easter break. Some of the café-Twitterers I follow went on a long break to the countryside (and Tweeted about it), others just turned off their social media for a few days. Elsewhere in the world you perhaps have different long weekends, Chinese New Year or Christmas. Perhaps during these holidays you manage to get a break in the countryside or by the coast. It is here that there is a link between an interesting recent study and a great use of a smartphone.  The study, by researchers at the University of Surrey and the London School of Economics, attempts to measure your ‘happiness’ while you are undertaking different activities in different locations, in urban environments, at work, or bird watching in the country.

Another great coffee outside, this time at Skylark cafe
Another great coffee outside, this time at Skylark cafe

Called the ‘mappiness‘ project, an app downloaded onto your iPhone (it is, sadly, only for iPhones), prompts the user to answer a question about their own perceived level of happiness at random instants. It then records the location of the phone (through GPS) and further asks the user to describe what they are doing. Over 1 million responses have so far been recorded through 20 000 participants. Perhaps unsurprisingly, the researchers have so far found that people tend to rate their happiness higher when they are outside, in natural environments and particularly in coastal areas. To me, it opens questions as to whether we should be attempting to quantify happiness or whether we should embrace the discussions of the humanities on this issue (less precise perhaps but by that very fact more complete and therefore more accurate). Perhaps these two approaches are complimentary. Nonetheless, the mappiness project remains an interesting study of a way in which you can use your phone in order to get a measure of where you should use your phone less.

Do get in touch and let me know what you think. Do you find it necessary to have some time out from social media or is Facebook your lifeline? Should cafés offer free wifi? Comments are always welcome (below) or you can get in touch by those two social media sites Twitter or Facebook. I do look forward to interacting with you there.

 

Categories
Coffee review Observations Science history slow

Reflections at Store St Espresso, Bloomsbury

Store St Espresso, coffee, Bloomsbury, UCL, London
Store St Espresso, Bloomsbury

I finally got around to visiting Store St Espresso two weeks ago while visiting the nearby Institute of Making’s 3rd birthday science-outreach party. Although the café was crowded, we managed to find a place to perch while we enjoyed a soya hot chocolate, caffé latte and my V60. Beans are from Square Mile while the V60 and filter coffee options featured guest roasters. Despite the narrow frontage, there is actually plenty of seating inside and people were happy to share tables with other customers when it got particularly busy. The café is well lit with sunlight streaming in through the sky lights above (indeed, the extra electric lighting indoors seemed a bit unnecessary given the amount of sunlight coming through the windows on such a good day). On the walls of the cafe were pieces of artwork, including quite a large pencil/charcoal piece right at the back of the cafe.

I was meeting a friend for coffee before going to the science event and so thought it would be good to combine a cafe-physics review with a visit to the science. It is always interesting to hear other people’s observations of the same space that you are ‘reviewing’. In this case, I was taken by the floor which showed some very interesting crack structures but what fascinated my friend (who was enjoying her caffe-latte) was the way that the sound from the stereo was reflecting from the bare walls, floor and ceiling. While cracks and fracture processes can be very interesting, perhaps it is worth following her observations as it leads, in a round about way, back to the coffee that she was drinking.

latte art, hot chocolate art, soya art
A caffe latte and a soya hot chocolate at Store St Espresso

While studying for my physics degree, a lecturer in a course on crystallography told us an anecdote. The story concerned a physicist walking past an apple orchard. As he was walking past, he noticed that at certain points he could hear the church bells from a distant church. As he walked on, the sound of the bells faded, before suddenly, he could hear them again. The physicist went on to derive the laws of X-ray diffraction, a technique that is now used routinely in order to understand the arrangement of atoms in crystals (like salt, diamond or caffeine). X-rays are part of the electromagnetic spectrum (just like visible light) but they have a very short wavelength.  The orchard had been inspirational to the physicist because, just as a crystal is a regular array of atoms, so the apple orchard is a regular array of trees; as you travel past an orchard (on the train, in a car or on foot), there are certain angles at which you can see straight through the trees, they have been planted in a 2D lattice. The church bells could only be heard at certain angles because of the way that the sound was being reflected from the multiple layers of the trees. The effect occurs because the sound made by church bells has a similar wavelength to the spacing of the trees (eg. ‘Big Ben’ chimes close to the note E, which has a wavelength of approximately 1m). The distance between atomic layers in a crystal is similar to the wavelength of the X-rays (the wavelength of X-rays frequently used for crystallography = 1.54 Å, size of the repeating structure in a salt crystal: 5.4 Å, 1 Å = 1/100000 of the smallest particle in an espresso grind). The physicist realised that the orchard affected the church bells in exactly the same way that the atoms in a crystal, be it salt, diamond or caffeine, will affect the deflection of X-rays. Suddenly, it became possible to actually ‘see’ crystal structures by measuring the angles at which the X-rays were scattered from substances.

bubbles on a soap solution
Not quite a regular 2D lattice. By controlling the size of the bubbles and the number of layers, you can simulate the crystal structure of different metals. Seems I need more practice in making bubbles of a similar size.

We can perhaps imagine an apple orchard but what do crystals look like? Crystals can come in many forms, all they need to be is a repeating structure of atoms through the solid. Some crystals are cubic, such as salt, some are hexagonal, others form different shapes. Metals, such as that making up the shiny espresso machine in the cafe are often a certain form of cubic structure and to visualise it, we can return to my friend’s caffé latte (via some soap). Two people who were instrumental in understanding X-ray diffraction were the father and son physicists, William Henry and William Lawrence Bragg. While attempting to make a model of crystal structures, William Lawrence Bragg found that the bubbles that could be formed on top of a soap solution were a very good approximation of the sort of crystal structures observed in metals (his paper can be found here). As they form, the soap bubbles (provided they are of similar size) form a regular cubic structure on the surface of the soap solution held together by capillary attraction, a very good model for the sort of bonding that occurs in metals. By controlling the size of the bubbles, the number of layers and the pressures on the layers of the bubbles, all sorts of phenomena that we usually see in crystals (grain boundaries, dislocations etc) could be made to form in “crystals” formed from soap bubbles. Why not look for such crystal structures in the foam of your cafe latte, though be careful to see how the size of the bubbles affects the arrangement of the bubbles through the foam structure.

Sadly, I have never found a reference to the story of the physicist and the apple orchard and it may even have been apocryphal. The closest reference I can find is that W. Lawrence Bragg (after whom the laws of X-ray diffraction are named) had a “moment of inspiration” for how X-rays would ‘reflect’ from multi-layers of atoms while he was walking in an area called “The Backs” in Cambridge. If any reader of this blog does know a good reference to this story I would be very much obliged if they could tell me in the comments section (below). To this day, I have been unable to pass by an orchard (or even a palm oil estate in Malaysia) without thinking about crystal structure, X-ray diffraction and church bells!

It seems that taking time to appreciate how sound is reflected (or diffracted) from objects, either in Store St Espresso or in an apple orchard, could be a very fruitful thing to do. If you have an observation of science in a cafe that you would like to share, please let me know here.

Store St Espresso can be found at 40 Store St. WC1E 7DB

The physics of X-ray diffraction and some great bubble crystal structures can be found in the Feynman Lectures on Physics, Vol II, 30-9 onwards.

Categories
General Home experiments Observations Sustainability/environmental

Clouds in my coffee

clouds over Lindisfarne
How do clouds form?

Does your coffee appear to steam more next to a polluted road than in the countryside?

This is a question that has been bothering me for some time. Perhaps it seems an odd question and maybe it is, but it is all about how clouds form. Maybe as you read this you can glance out the window where you will see blue skies and fluffy white clouds. Each cloud consists of millions, billions, of water droplets. Indeed, according to the Met Office, just one cubic metre of a cloud contains 1 hundred million water droplets. We know something about the size of these droplets because the clouds appear white which is due to the way that particles, including water droplets, scatter sunlight. Clouds appear white because the water droplets scatter the sunlight in all directions. In contrast, the particles in a cloudless sky scatter blue light (from the Sun) more than they scatter red. Consequently, from our viewpoint, the scattered light from the clouds appears white while the sky appears blue. The sort of directionless light scattering that comes from the clouds happens when the scattering sites (ie. the water droplets) are of a size that is comparable to, or larger than, the wavelength of light. This means that the water droplets in a cloud have to be larger than about 700 nm in diameter (or approximately just less than a tenth of the size of the smallest particle in an espresso grind). The particles in the atmosphere on the other hand scatter blue light more than they scatter red light because they are smaller than the wavelength of the blue light. You can find out more about light scattering, blue skies and cloudy days, with a simple experiment involving a glass of milk, more details can be found here.

glass of milk, sky, Mie scattering
A glass of (diluted) milk can provide clues as to the colours of the clouds in the sky as well as the sky itself

So each of the one hundred million water droplets in a cubic metre of cloud is at least about a micron in diameter. We can then estimate how many water molecules make up one droplet by dividing the mass of a droplet of this size by the mass of one water molecule. This turns out to be more than 1000 million water molecules that are needed to make up one droplet of cloud. So, 1000 million water molecules are needed for each of the 100 million drops that make up one, just one, cubic metre of cloud. These numbers are truly huge.

But can so many molecules just spontaneously form into so many water droplets? Unlike a snowball, the water droplet in a cloud cannot start very small and accumulate more water, getting larger and larger until it forms a droplet of about a micron in size. Water droplets that are much smaller than about a micron are unstable because the water molecules in the drop evaporate out of it before they get a chance to form into a cloud (precise details depend on the exact atmospheric conditions). Water droplets need to come ‘ready formed’ to make the clouds which seems unlikely. So how is it that clouds can form?

Condensation on mug in CGaF
Look carefully at the rim of the mug. Do you see the condensation?

It turns out that the water droplets form by the water condensing onto something in the atmosphere. That something could be dust, or salt or one of the many other sorts of aerosol that are floating around in our skies. Just as with a cold mug filled with hot coffee, the dust in the air gives the water molecules a cold surface onto which they can condense. This sort of water droplet can ‘snowball’ into the bigger droplets that form clouds because the water is now condensing onto something and so does not evaporate off again so easily. At the heart of each water droplet in a cloud is a bit of dust or a tiny crystal of salt. Which brings me back to my question. It is much more dusty along a polluted road  than it is in the clean air of the countryside. Is this going to be enough of an effect to affect the probability of cloud formation? Does your coffee steam more as you cross the road than when you walk through the park?

It is a question that demands an experiment (and associated video). Last year, the Met Office suggested this simple experiment for observing clouds in a bottle. Unfortunately however, I have yet to make this experiment work in a way that would allow me to test whether polluted air produces thicker clouds than cleaner air. If you have any suggestions as to a good experiment (that will work on camera!) please let me know either in the comments section, by emailing me, or on Facebook. In the meanwhile, I’d be interested to know what you think, so if you think this post is about you, please let me know.